There are a number of positionable devices which are rotated to a desired orientation. One such device is an armboard which is rotatably associated with an X-ray table.
Cardiac, neurological and general vascular studies frequently require an X-ray table for examining patients. Viewing a patient's body is particularly important for guiding catheters through arteries or veins. The body is frequently accessed through an arm of the patient positioned on an armboard of an armboard mounting assembly. This technique is commonly referred to as the Sones approach. An armboard mounting assembly has an armboard mount attached to the X-ray table for mounting one or more armboards which extend from the mounting assembly at a pivot assembly.
An X-ray table typically rests between a radiological source, such as an X-ray tube, and an imaging plate responsive to a viewing screen or including an imaging film. Most areas of conventional tables and armboards are by necessity radiologically translucent to allow X-rays to reach the imaging plate. However, important areas of X-ray tables and accessories often contain radiologically opaque structural material such as steel. Details of the patient's body overlaying the opaque structure are obscured and physicians must navigate a catheter blindly through these bodily regions. One such region is the patient's shoulder overlaying the pivot assembly between the armboard and the armboard mount. A conventional armboard has a steel pin protruding from a steel disk embedded in the board. Steel is used to provide strength and durability. Radiological opacity of the conventional pivot assembly presents great difficulty in passing a catheter through the proper vein or artery in the shoulder area. Further, the pivot assembly is often attached to the armboard mount with steel connector pins. Commonly, the connector pins insert into a steel cradle mount which bridges the X-ray table and provides support for opposing armboards. These radiologically opaque structures further reduce the effective viewing areas of a patient.
Conventional armboards exhibit other disadvantages. Accepted hospital practices prevent radiologists from touching objects outside the sterile zone. The locking mechanism for many armboards are located on the underside of the armboard and table in a non-sterile area, where it may not be accessed during medical procedures. Thus the need to move the armboard and the restriction against touching non-sterile areas can create a conflict for the attending physicians. These locks are active locking systems requiring action to lock or unlock them. When locked, it is possible to damage them through forcible, inadvertent movement. Armboard mounts are secured with separate active locking systems often involving screw or clamps which are not X-ray translucent.
The metal components associated with conventional armboard designs make them incompatible with NMR procedures. NMR scanning requires that the study area be free of ferrous or other magnetic material which is or can become magnetized. The magnetic material interferes with the varying magnetic field used in NMR procedures. The study area must also be free of electrically conductive material for the safety of the patient and the attendants. These requirements have prevented the use of a pivoting, locking armboard during such procedures.
One conventional armboard mount is not radiologically translucent and relies on an upward translational movement of the armboard to disengage the armboard and enable rotation to a desired position. However, the weight of the entire arm of the patient must be overcome to accomplish the translational disengagement.